The present invention relates generally to computing networks and relates more particularly to the expansion of peer-to-peer data transfer networks.
FIG. 1 is a schematic diagram of a network 100 of nodes (e.g., computing devices) interacting in a peer-to-peer (P2P) manner. Generally, a requesting node 101 sends a search message 105 (e.g., containing keywords relating to data that the requesting node 101 wishes to locate) to at least one intermediate node 111 in communication with the requesting node 101 via a peer connection. The intermediate node 111 receives the search message 105 and forwards the search message 105 to at least one additional node 111. Eventually, the search message 105 reaches at least one responding node 103 having the requested data (in some cases, the first intermediate node 111 to which the search message 105 is forwarded will also be a responding node 103). At least one responding node 103 then sends a response message 107 back to the requesting node 101, e.g., via the intermediate nodes 111. The requesting node 101 then requests the relevant data from a responding node 103 by connecting directly to the responding node 103, e.g., via direct connection 109.
In conventional P2P systems, messages including the search message 105 and the response message 107 have a limited time to live or hop count. That is, a message will expire once it has been forwarded to a predefined maximum number of nodes 101, 103 or 111. Thus, if the requesting node 101 generates a second search message having a time to live of four, and a node at which the requested data resides (e.g., node 113) is more than four “hops” away from the requesting node 101, the second search message will expire before the requested data is obtained. This problem can be reduced by increasing the search message's time to live or by increasing a number of peer connections per node; however, either will cause an increase in network traffic (the former increase being exponential due to the fan out nature of the network 100).
Thus, there is a need in the art for a method and apparatus for efficiently expanding a P2P network.